(a) Field of the Invention
The present invention relates to a sensor unit, and more particularly, to a sensor that uses a transmitter to transmit a signal at a predetermined frequency (e.g., infrared light) and a receiver that receives the reflected signal to detect vibration, a contact, an approaching motion/movement, or an attempted theft/break in.
(b) Description of the Related Art
Generally, an impact detecting sensor uses an acceleration sensor (e.g., an accelerometer) to detect the variation of speed that is generated by an impact, which may then trigger an alarm. An impact in a random direction can be detected by using a conventional acceleration sensor. Unfortunately, it is difficult to use a conventional acceleration sensor to detect an approaching contact that does not result in an impact and thereby prevent impact damage to a vehicle.
An indoor motion detecting device for a vehicle can radiate ultrasonic waves throughout the interior of a vehicle by using an ultrasonic sensor and to detect the reflected ultrasonic waves. Unfortunately, such a conventional motion detecting device has several disadvantages. For example, this type of motion detecting device uses an ultrasonic wave sensor, which is expensive to produce and also requires a lot of power to operate. Additionally, because such conventional motion detecting devices are implemented in the interior of a vehicle, they cannot be used to detect an approaching contact on the outside of the vehicle. Accordingly, there is a need in the art for a sensor that will efficiently detect an impending contact to an exterior or interior surface of the vehicle surface of the vehicle, to aid in the prevention of a vehicle accident.